4x52
From Proteopedia
Human PARP13 (ZC3HAV1), C-Terminal PARP Domain (H810N; N830Y variant)
Structural highlights
FunctionZCCHV_HUMAN Antiviral protein which inhibits the replication of viruses by recruiting the cellular RNA degradation machineries to degrade the viral mRNAs. Binds to a ZAP-responsive element (ZRE) present in the target viral mRNA, recruits cellular poly(A)-specific ribonuclease PARN to remove the poly(A) tail, and the 3'-5' exoribonuclease complex exosome to degrade the RNA body from the 3'-end. It also recruits the decapping complex DCP1-DCP2 through RNA helicase p72 (DDX17) to remove the cap structure of the viral mRNA to initiate its degradation from the 5'-end. Its target viruses belong to families which include retroviridae: human immunodeficiency virus type 1 (HIV-1), moloney and murine leukemia virus (MoMLV) and xenotropic MuLV-related virus (XMRV), filoviridae: ebola virus (EBOV) and marburg virus (MARV), togaviridae: sindbis virus (SINV) and Ross river virus (RRV). Specifically targets the multiply spliced but not unspliced or singly spliced HIV-1 mRNAs for degradation. Isoform 1 is a more potent viral inhibitor than isoform 2. Isoform 2 acts as a positive regulator of DDX58/RIG-I signaling resulting in activation of the downstream effector IRF3 leading to the expression of type I IFNs and IFN stimulated genes (ISGs).[1] [2] [3] [4] Publication Abstract from PubMedThe mammalian poly(ADP-ribose) polymerase (PARP) family are ADP-ribosyltransferases with diphtheria toxin homology (ARTD). Most members have mono-ADP-ribosyltransferase activity. PARP13/ARTD13, also called zinc finger antiviral protein (ZAP), has roles in viral immunity and microRNA mediated stress responses. PARP13 features a divergent PARP homology domain missing a PARP consensus sequence motif; the domain has enigmatic functions and apparently lacks catalytic activity. We used X-ray crystallography, molecular dynamics simulations and biochemical analyses to investigate the structural requirements for ADP-ribosyltransferase activity in human PARP13 and two of its functional partners in stress granules, PARP12/ARTD12, and PARP15/ BAL3/ARTD7. The crystal structure of the PARP homology domain of PARP13 shows obstruction of the canonical active site, precluding NAD+ binding. Molecular dynamics simulations indicate that this closed cleft conformation is maintained in solution. Introducing consensus side chains in PARP13 did not result in 3-aminobenzamide binding, but in further closure of the site. Three-dimensional alignment of the PARP homology domains of PARP13, PARP12, and PARP15 illustrates placement of PARP13 residues that deviate from the PARP family consensus. Introducing either one of two of these side chains into the corresponding positions in PARP15 abolished PARP15 ADP-ribosyltransferase activity. Taken together, our results show that PARP13 lacks the structural requirements for ADP-ribosyltransferase activity. Structural Basis for Lack of ADP-Ribosyltransferase Activity in Poly(ADP-Ribose) Polymerase-13/Zinc Finger Antiviral Protein.,Karlberg T, Klepsch M, Thorsell AG, Andersson CD, Linusson A, Schuler H J Biol Chem. 2015 Jan 29. pii: jbc.M114.630160. PMID:25635049[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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